Missing Chapters of Geological History. 27 



re-creations of species, as the method of nature, seems to stand 

 out strongly as an idea utterly unworthy of an Almighty and 

 Allwise Power. Perfection requires that there should be a pro- 

 vision for whatever may happen. The course of nature has been 

 found to involve alternations of greater or less regularity in 

 the accumulation of deposits on the globe, and the conversion 

 of them into rocks. Long periods of comparative rest have been 

 succeeded by long periods of comparative disturbance and 

 movement. It is highly probable, almost certain, that this 

 alternation has always been adopted, and thus perhaps in 

 reality it may be that the views of those geologists who would 

 avoid, and those who would admit, cataclysmic action, will 

 ultimately be found to agree. But it is not within our expe- 

 rience in any cataclysmic action that a sudden destruction of 

 all life should be a part of the disturbance. As far as we know 

 all disturbance is local as well as sudden, and modification of 

 species may be so to. During repose there is little change, 

 during disturbance there is much. In other words, animals 

 and plants adapt themselves, or are adapted by some universal 

 law of growth and development, and they do this gradually and 

 slowly if the alteration of external conditions is slow, but rapidly 

 and completely if the change is quick. But as there is always 

 some change going on in the external inorganic world, so there 

 is always corresponding change in the organic world ; and thus 

 species are constantly being introduced, culminating, and 

 decaying. 



To obtain a true notion of the workings of nature then, we 

 must study the continuous formations of the Secondary period, 

 endeavouring to judge of time by comparing changes formerly 

 with changes now. The tables given by Professor Eamsay will 

 enable the student to do this in some measure ; but he must 

 not suppose that he thus obtains the precise truth or all the 

 truth. In the first place, the number of species found in 

 different formations is always increasing by discovery and 

 research in the field, and the proportions are, of course, sub- 

 ject to change. In the next place, this number is always 

 either increasing or diminishing by the work in the closet, as 

 the palaeontologist makes or unmakes species; and this is, 

 unhappily, a source of confusion that must long remain. 

 Naturalists cannot agree as to what external characters are 

 sufficient to form species, and it is almost certain that they 

 have generally erred in admitting mere accidental varieties of 

 form or development, and giving a specific value to such small 

 modifications. Time probably will greatly diminish the number 

 of species whose names must be learnt ; but for the purposes 

 of the inquiry at present before us, those marked varieties that 

 are easily recognized and are permanent, whether they be or 



